As strength and conditioning training has gotten better and better over the years, NFL players have become stronger and faster. Running backs like Adrian Peterson can both bust through lanes without a lead-blocker and also break tackles on short-yardage runs. Slot-receivers like Wes Welker can slip into the middle of the field, then burst for big gains after the catch.

Slower, strength-based offensive positions like the fullback and tight end are becoming redundant.

Teams just don’t need as much talent at these spots because they have other position-players who can match the muscle without sacrificing speed. And when teams need muscle, offensive linemen (think Nate Solder) have become fit enough to double as blockers.

With only two marquee tight ends in the NFL through the first decade of the new millennium – Tony Gonzalez and Antonio Gates – the position was in danger of extinction.

Then Rob Gronkowski arrived, and with him a second renaissance for tight ends.

Fullback Fading Away; Tight End, Too

A look at Pro Football Hall of Fame inductees shows how the league has moved away from certain positions. Gale Sayers was the last halfback to make it to the Hall of Fame, and his career ended in 1971. The fullback seems headed that way as well: Larry Csonka – whose career ended in 1979 – was the last fullback inducted.

The tight end, meanwhile is the third-least-represented position in the Hall of Fame, trailing just place-kickers and the near-extinct fullbacks. Only eight modern-era tight ends are in the Hall of Fame, and the only one who played in the 1990s or later is Shannon Sharpe. Of the remaining seven, most played in the 60s and 70s.

Y2K Almost Killed the Tight End

Though tight ends had hung around longer than the fullbacks, the NFL looked by the mid 2000s like it was sending the position the way of leather helmets.

From 2001 to 2010, a tight end only finished among the top 10 receivers in yardage once: Gonzalez, who finished seventh in 2004. Otherwise, the top tight end – Gonzalez or Gates in eight of those 10 years – averaged a below-18th final ranking in the NFL. Tight ends have been decent scorers, however, finishing among the top 10 for touchdown receptions nine times during that decade, and six times placing among the top five.

Gronkowski entered the NFL in 2010, finishing tied for seventh in the NFL with 10 touchdown catches. He took a gigantic leap forward this past season, setting NFL single-season records for tight ends with 1,327 yards (sixth in the NFL, a 21st century best among tight ends) and 17 touchdowns (first in the NFL).

Gronkowski isn’t the only tight end who had a banner 2011 season: New Orleans Saint Jimmy Graham finished seventh in the league with 1,310 yards and tied for fourth with 11 TD catches. Gronkowski and Graham present a new model for the tight end.

Turning Size into a Skill

Gronkowski and Graham have nearly identical physical makeups: both are 6-foot-6, with Gronkowski weighing 265 pounds and Graham just five pounds fewer. The two use their bodies in very similar ways.

By matching their size with sure-handed catching ability, both Gronkowski and Graham provide a bigger target for quarterbacks than most wide receivers. Linebackers can’t keep up with them while defensive backs can’t contain their giant wingspans.

Instead of outrunning his defenders, Gronkowski has opted to out-jump, out-muscle and out-reach them. Closer defenders means a higher chance of a defensed pass, but once Gronkowski catches the ball – which happens over 70 percent of the time – the defender finds himself badly positioned to tackle the brawny tight end. That’s led to numerous broken tackles and big yardage after the catch.

Gronkowski finished the season with 632 yards after catches (YAC), or 47.6 percent of his total yardage. That’s a higher percentage than anyone else among the top 20 receivers in the league, including top YACer Welker. Gronkowski has earned all that YAC by simply refusing to be tackled, no matter whether he faces a lone defensive back or three linebackers.

Thanks to Gronkowski, college tight ends with dreams of the NFL need not fear transitioning into wide receivers. Gronkowski has turned the tight end’s increased size and muscle mass into a uniquely advantageous skill-set. And until defensive backs get stronger or linebackers get faster, Gronkowski and tight ends like him will remain monstrously un-defendable.